KAD 44 injector return leak

[joae]

Having problems in getting the return connection on the injectors to seal properly.
Problem occured when injector hade been removed and refitted and I then loosened the injectors in order for them to line up properly with the return rail. This improved the seal but not completely.
So now I am using new copper seals and thigthen the screws as much as I dare but it is still a slight leak on 2-3 injectors.

Anyone been there and know how to fix. This should be super simple with clean surfaces and new washers...

 

[volvopaul]

Having problems in getting the return connection on the injectors to seal properly.
Problem occured when injector hade been removed and refitted and I then loosened the injectors in order for them to line up properly with the return rail. This improved the seal but not completely.
So now I am using new copper seals and thigthen the screws as much as I dare but it is still a slight leak on 2-3 injectors.

Anyone been there and know how to fix. This should be super simple with clean surfaces and new washers...

Are you using the correct new style washers they are larger diameter than the old ones , I’ve removed hundreds over the years never had a diesel leak

 

[spannerman]

As VP said, only had a leak when it wasn’t tightened enough.

 

[joae]

Thanks for the repiles!
Found an old picture. This is what it looks like. I never used any other sizes. I assume you are talking about the outer dia of the washer? Ther where also some alu washers in the kit but they had a very large inner dia and did not fit very vell so I used the copper ones instead.
I think i will have to inspect the parts more closely as you say this should be a very simple seal and I never had any problems with these types of seals if new washers are used (cant even remember that I have had any leaks even when reusing old washers...)

 

[volvopaul]

Thanks for the repiles!
Found an old picture. This is what it looks like. I never used any other sizes. I assume you are talking about the outer dia of the washer? Ther where also some alu washers in the kit but they had a very large inner dia and did not fit very vell so I used the copper ones instead.
I think i will have to inspect the parts more closely as you say this should be a very simple seal and I never had any problems with these types of seals if new washers are used (cant even remember that I have had any leaks even when reusing old washers...)

That’s an aluminium washer , they should be copper

 

[joae]

That’s an aluminium washer , they should be copper

No its copper, but I agree that the glare from the cameras flash makes it look shiny. Look on the top there you see the copper color. But anyway I never used aluminium washers and I think there are some thing I have missed here because this should be so simple.
I have some new Volvo original copper washers and I will try to inspect the surfaces again and assemble it again.

The metod I use to identify a leak is to apply about 0.5 bar air in the return pipe from the injectors before it joins the return from the pump and I then apply soapy water to the connections. This metod is to not have a messy diesel leak after final assembly.
By the way the engine(s) are in the shop right now for a major overhaul so now is the time to do it right ;-)

 

[Beneteau381]

No its copper, but I agree that the glare from the cameras flash makes it look shiny. Look on the top there you see the copper color. But anyway I never used aluminium washers and I think there are some thing I have missed here because this should be so simple.
I have some new Volvo original copper washers and I will try to inspect the surfaces again and assemble it again.

The metod I use to identify a leak is to apply about 0.5 bar air in the return pipe from the injectors before it joins the return from the pump and I then apply soapy water to the connections. This metod is to not have a messy diesel leak after final assembly.
By the way the engine(s) are in the shop right now for a major overhaul so now is the time to do it right ;-)

Do what Ive just done, anneal them! Old fashioned, taught to me as an apprentice over 50 years ago. Dangle on a bit of wire in a gas hob flame until they are cherryred then drop them in cold water. Then clean with some scotchpad.

 

[joae]

Gave it a new try yesterday and documented the parts with my phone.
The surfaces seem clean and straight to me.
The washer fits just inside the recess of the injector.
I assume the washers are annealed when new so if not reusing them there would be no need for annealing.

After assembly I applied airpressure of roughly 1 bar and when soapy water is applied there are some very small bubbles.

I give up on this now in hope of the my method of leak testing is too revealing and that during normal operation I will not see any diesel leak.

This is accessible after the engines are installed so the work will maybe continue then...

 

[joae]

Also Thanks for your replies. I will try to remeber to give an update on this when I know the real world result ;-)

 

[joae]

Follow up: Dont know what I did wrong but the seals seemed to leak when pressurized with air and applied soapy water, but they haven't leaked a bit diesel to what I can see during the summer season (~50 h).
Wonder if my testing was wrong. The seals are very simple and should be completely tight even with air. It is possible that it has continued to leak but so small that it don't show due to that the leakage evaporates.

Anyhow I dont bother with this any more, there are other things to worry about ;-)

 

[Moodysailor]

Follow up: Dont know what I did wrong but the seals seemed to leak when pressurized with air and applied soapy water, but they haven't leaked a bit diesel to what I can see during the summer season (~50 h).
Wonder if my testing was wrong. The seals are very simple and should be completely tight even with air. It is possible that it has continued to leak but so small that it don't show due to that the leakage evaporates.

Anyhow I dont bother with this any more, there are other things to worry about ;-)

I am not surprised about this, the amount of air pressure you were putting into the line is much greater than the return fuel pressure.

Glad it's all sorted with no leaks - i've also not seen any issues with these as long as new washers are used when refitting.

 

[simonfraser]

air molecules smaller than diesel ones ?

nasa has great fun with sealing hydrogen lines

 

[DavidJ]

There must be a torque setting for the bolt. I always find torque settings just a bit more than I’m comfortable with by feel so you may be able to get another few degrees. Although you don’t have a problem with fuel, the design should pass your air pressure test.

 

[joae]

As often, gas escapes easier than liquid but this type of seal is dead simple and works for pressures well over 100 bar in liquid and gas.

About the torque this is interesting topic as the bolts are only partially threaded and the female thread is in the injector and you dont want to risk this. I did not use a torque wrench other than my wrist ;-) You dont want to have the feeling of the bolt getting easier to turn when you tightening it. So maybe i was a little too cautious.

Thanks for you ideas and support!

 

[QBhoy]

As said. Anneal them. Will see them ok.